linux-kernel - Re: [PATCH 1/2]pstore: Move timestamp collection code to common pstore place

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Date:   Tue, 23 May 2017 13:42:51 +0530
From:   Ankit Kumar <ankit@...ux.vnet.ibm.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "mahesh@...ux.vnet.ibm.com" <mahesh@...ux.vnet.ibm.com>,
        Hari Bathini <hbathini@...ux.vnet.ibm.com>,
        hegdevasant@...ux.vnet.ibm.com
Subject: Re: [PATCH 1/2]pstore: Move timestamp collection code to common
 pstore place

Hi Kees,

Thank you so much for your response.



On Tuesday 23 May 2017 05:07 AM, Kees Cook wrote:
> On Mon, May 22, 2017 at 3:20 AM, Ankit Kumar <ankit@...ux.vnet.ibm.com> wrote:
>> Current pstore code(ram.c) gets dump timestamp and make it part of header.
>> Different diffent architecture uses different header format and hence it
>> won't be good idea to make ramoops_write_kmsg_hdr/ramoops_read_kmsg_hdr
>> part of generic pstore code.
>>
>> ramoops_write_kmsg_hdr calls __getnstimeofday to get timestamp and also
>> takes care of condition if timekeeping has not resumed.
>>
>> This patch moves code for retrieving timestamp to common place and hence
>> can be used by other functions as well.
> Ah! Heh, funny, I had just done a version of this while working on EFI
> pstore fixes. Here's what I did instead:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/commit/?h=pstore/fixes&id=ea209b760f104daf0cf62953090b66c5628b0842
>
> This makes it so the time field is prepopulated for all backend
> writes, which should simplify things (no need to have the backends
> call out).


Above mentioned patch moves code to common place and also simplifies things.
I agree, My patch is not required anymore.

Thank you;

~Ankit




> -Kees
>
>> Signed-off-by: Ankit Kumar <ankit@...ux.vnet.ibm.com>
>> ---
>>   fs/pstore/internal.h |  1 +
>>   fs/pstore/platform.c | 13 +++++++++++++
>>   fs/pstore/ram.c      |  9 ++++-----
>>   3 files changed, 18 insertions(+), 5 deletions(-)
>>
>> diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
>> index c416e65..339dcdc 100644
>> --- a/fs/pstore/internal.h
>> +++ b/fs/pstore/internal.h
>> @@ -22,6 +22,7 @@ static inline void pstore_unregister_pmsg(void) {}
>>   #endif
>>
>>   extern struct pstore_info *psinfo;
>> +void pstore_get_timestamp(struct timespec *timestamp);
>>
>>   extern void    pstore_set_kmsg_bytes(int);
>>   extern void    pstore_get_records(int);
>> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
>> index d468eec..5cb25b0 100644
>> --- a/fs/pstore/platform.c
>> +++ b/fs/pstore/platform.c
>> @@ -474,6 +474,19 @@ static size_t copy_kmsg_to_buffer(int hsize, size_t len)
>>          return total_len;
>>   }
>>
>> +void pstore_get_timestamp(struct timespec *timestamp)
>> +{
>> +       if (!timestamp)
>> +               return;
>> +
>> +       /* Report zeroed timestamp if called before timekeeping has resumed. */
>> +       if (__getnstimeofday(timestamp)) {
>> +               timestamp->tv_sec = 0;
>> +               timestamp->tv_nsec = 0;
>> +       }
>> +}
>> +EXPORT_SYMBOL_GPL(pstore_get_timestamp);
>> +
>>   /*
>>    * callback from kmsg_dump. (s2,l2) has the most recently
>>    * written bytes, older bytes are in (s1,l1). Save as much
>> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
>> index 5cb022c..e39297d 100644
>> --- a/fs/pstore/ram.c
>> +++ b/fs/pstore/ram.c
>> @@ -37,6 +37,8 @@
>>   #include <linux/of.h>
>>   #include <linux/of_address.h>
>>
>> +#include "internal.h"
>> +
>>   #define RAMOOPS_KERNMSG_HDR "===="
>>   #define MIN_MEM_SIZE 4096UL
>>
>> @@ -362,11 +364,8 @@ static size_t ramoops_write_kmsg_hdr(struct persistent_ram_zone *prz,
>>          struct timespec timestamp;
>>          size_t len;
>>
>> -       /* Report zeroed timestamp if called before timekeeping has resumed. */
>> -       if (__getnstimeofday(&timestamp)) {
>> -               timestamp.tv_sec = 0;
>> -               timestamp.tv_nsec = 0;
>> -       }
>> +       pstore_get_timestamp(&timestamp);
>> +
>>          hdr = kasprintf(GFP_ATOMIC, RAMOOPS_KERNMSG_HDR "%lu.%lu-%c\n",
>>                  (long)timestamp.tv_sec, (long)(timestamp.tv_nsec / 1000),
>>                  compressed ? 'C' : 'D');
>> --
>> 2.7.4
>>
>
>